This invention relates in general to railroad cars, and in particular, to couplers for rotary dump cars. Rotary dump cars and couplings for such cars are shown in U.S. Pat. No. 4,595,109 issued Jun. 17, 1986 to Carl McClurg and originally assigned to Buckeye International, Inc. of Columbus, Ohio. As exemplied by and shown in this patent, rotary dump cars have long been in use as railroad cars. The cars may be positioned over dump sites and rotated about the longitudinal axes of aligned couplers to dump the car contents into sites adjacent and beneath the cars. Also as shown in this patent, a desirable coupler for application in rotary dump cars includes a coupler head with a spindle in a housing. The spindle has external bearing surfaces arranged for rotary contact with the housing during rotation of the car relative to the adjacent cars. The spindle of the coupler also includes an enlarged flange for bearing of the spindle against the housing for draft loads. In buff loading, the free end of the spindle abuts a shim which abuts the housing, thereby carrying the buff load. The general structure of the identified patent has been highly desirable and continues in substantial commercial production.
Experience has revealed that replacement of the shim over time is desirable as wear occurs in the coupler structure. That is, increased thickness shims are appropriate for installation in worn couplings. As a result, while U.S. Pat. No. 4,595,109 reveals a bottom enclosure casting 40 welded to a housing 16, referring to FIG. 3 of the patent, in the area to the left of the enlarged portion 70 of the spindle 14 and at the bottom of the structure, the welded bottom enclosure casting 40 has in the past been replaced with tabs which are releasably held in place by bolts. Use of the bolted tabs has allowed for replacement of shims over time. However, use of the bolted tabs has also resulted in damage to the bolts and loss of the tabs and shims, which is undesirable. To overcome the damage to the bolts and loss of shims, the size 3/8" bolts initially used have been replaced by 1/2" grade 8 bolts and then by 1/2" grade 9 bolts. However, continued damage to the bolts and loss of the tabs and shims has been experienced.
U.S. Pat. No. 4,595,109 is incorporated by reference.